White House Press Secretary Robert Gibbs speaks at the daily press briefing in Washington July 26. (AP Photo)

The Obama administration on Monday called the release of thousands of classified documents on the Afghanistan war a "breach of federal law," as prominent senators said the government needs to press charges in the case.

"Somebody ought to be wearing an orange jumpsuit," said Missouri Sen. Kit Bond, ranking Republican on the Senate Intelligence Committee.

White House Press Secretary Robert Gibbs faced a barrage of questions on the leak at the daily press briefing Monday. He dismissed the contents as devoid of "broad revelations," but nevertheless expressed concern that sensitive information would be detailed in the more than 75,000 documents leaked. An expected 15,000 more also are expected to be revealed.

"You have the potential for names and for operations and for programs to be out there in the public domain, that it, besides being against the law, has the potential to be very harmful to those that are in our military, those that are cooperating with our military, and those that are working to keep us safe," Gibbs said.

Sen. Dianne Feinstein, D-Calif., called the leaks "a serious breach of national security."

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"This was a clear and pronounced effort to secure several years' worth of communications, emails and reports, and without any approval to put it out to the world," Feinstein said, calling for the military to investigate.

And Sen. John McCain, calling the release "deeply troubling," said: "The source of this harmful leak within the U.S. government should face the full penalties of the law."

Though a Pentagon spokesman said Monday morning that there is no investigation "at this point" and the Justice Department would not comment on the matter, Pentagon spokesman Geoff Morrell told Fox News the department wants to find out who originally leaked the information to "make sure there's not any more coming." He said it remains to be seen whether any action will be taken against those involved in the leak.

The document dump over the weekend was not the last of it. WikiLeaks.org founder Julian Assange said he released 76,000 documents, but that the remaining 15,000 were being withheld pending further review. He said some would be released and others would be withheld until it is safe to release them.

Pentagon spokesman Col. Dave Lapan told reporters Monday that the military takes the leak "very seriously" and is in the process of reviewing the information. Lapan said it could take "weeks" to review all of them as they are released.

"As they are made available, we will be looking at them to try to determine the potential damage to lives of our service members and our coalition partners, whether they reveal sources and methods and any potential damage to national security," he said.

Lapan later said that it was "logical to assume" that Pfc. Bradley Manning, already charged in another release of classified materials to WikiLeaks, would be a person of interest in the new leak, but all potential sources are being looked at.

Earlier, the Obama administration said the document dump would not hurt the war effort, but condemned the release as "irresponsible" and said Wikileaks "made no effort" to contact the federal government before releasing them.

A U.S. official warned that much of the material covers "unvarnished, unvetted, uncorroborated reporting" from people in the region who may have "agendas." Officials also accused Wikileaks of having an anti-Afghanistan war agenda.

"Wikileaks seems to have an agenda of its own -- and it goes beyond publishing classified information for the benefit of others to analyze," the U.S. official said. "They purport to be objective at the same time they offer their own opinions of the war. That's truly shameful. No one is denying that there are real challenges in Afghanistan, but you'd never want Wikileaks to be your meteorologist. They see nothing but dark clouds. As we all know, weather cycles are more nuanced than that."

The classified U.S. records on the war, marking one of the largest unauthorized disclosures in military history, cover a time period that largely predates the Obama administration as well as the new strategy and surge announced at the end of 2009. They apparently cover a period from January 2004 to December 2009.

The documents cover much of what the public already knows about the troubled nine-year conflict: U.S. special-ops forces have targeted militants without trial, Afghans have been killed by accident and U.S. officials have been infuriated by alleged Pakistani intelligence cooperation with the very insurgent groups bent on killing Americans.

National Security Adviser Gen. James Jones said in a written statement that relations with the Pakistanis and other trouble spots have improved since the end of 2009.

"On December 1, 2009, President Obama announced a new strategy with a substantial increase in resources for Afghanistan, and increased focus on Al Qaeda and Taliban safe-havens in Pakistan, precisely because of the grave situation that had developed over several years," he said.

Jones lambasted Wikileaks.org for releasing the massive trove of documents.

"The United States strongly condemns the disclosure of classified information by individuals and organizations which could put the lives of Americans and our partners at risk, and threaten our national security," he said.

WikiLeaks posted the documents Sunday. The New York Times, London's Guardian newspaper and the German weekly Der Spiegel were given early access to the records.

Assange, who held a press conference in London to address the documents, said Monday his organization has "no reason to doubt the reliability" of the records. He said the records will "shape an understanding" of the war's first six years, though he said the documents did not include any "top secret" information.

He claimed that "there does appear to be evidence of war crimes in this material," in a reference to at least seven reported civilian casualties.

A White House aide said many of the concerns addressed in the documents had been addressed publicly by U.S. officials.

Pakistan's Ambassador Husain Haqqani said the documents "do not reflect the current on-ground realities," in which his country and Washington are "jointly endeavoring to defeat Al Qaeda and its Taliban allies."

Senate Foreign Relations Committee Chairman John Kerry, D-Mass., though, suggested the release could lead to a change in policy. He said in a written statement that "however illegally" the documents were released, they raise "serious questions" about U.S. policy toward the region.

"Those policies are at a critical stage and these documents may very well underscore the stakes and make the calibrations needed to get the policy right more urgent," he said.

The U.S. and Pakistan assigned teams of analysts to read the records online to assess whether sources or locations were at risk.

The Guardian said the documents "fail to provide a convincing smoking gun" for complicity between the Pakistan intelligence services and the Taliban.

The New York Times interpreted the papers differently, saying they reveal that only a short time ago, there was far less harmony in U.S. and Pakistani exchanges.

The Times said the "raw intelligence assessments" by lower level military officers suggest that Pakistan "allows representatives of its spy service to meet directly with the Taliban in secret strategy sessions to organize networks of militant groups that fight against American soldiers in Afghanistan, and even hatch plots to assassinate Afghan leaders."